Fuel storage systems for storing a fuel for a vehicle generally include a tank, a check valve, and a fuel intake tube. The tank stores the fuel until needed by an engine. The check valve is coupled to the tank, and is configured to allow fuel flow from the fuel intake tube into the tank and prevent fuel flow in an opposite direction out of the tank and back through the fuel intake tube.
In order to prevent siphoning of the fuel stored within the tank, the fuel storage system may include an anti-siphon device. The anti-siphon device is disposed somewhere within or between the fuel intake tube and/or the check valve. The anti-siphon device prevents passage of an object, e.g., a siphon tube, therethrough, thereby preventing siphoning of the fuel stored within the tank.
Anti-siphon devices for gasoline powered vehicles have previously included a mesh screen or the like having many small sized apertures through which the fuel flows when filling the tank. For alcohol based fuels, such as E-85, the large apertures tend to vaporize a larger percentage of the alcohol based fuel during filling than occurs with gasoline. The increased vaporization of the alcohol based fuel increases the backpressure within the tank, which reduces the storage capacity of the tank, or alternatively, requires a larger carbon canister to compensate for the increased fuel vaporization.
Furthermore, fluid and/or vapor backpressure within the fuel storage system may lead to a premature shut-off condition, in which a fuel filler nozzle automatically shuts off when the back pressure rises above a certain level. The back pressure within the fuel system may be caused by flow obstructions, such as a fill pipe diameter, a sharp bend in the fill pipe, a static pressure head of the fuel in the fuel tank, a check valve in the fill pipe, etc.